Sound off! What apps help you get things done?

For the procrastinators among us, I share your philosophy: Why do today what you can put off until tomorrow? Sadly, the people who sign our paychecks don't really agree; they strongly encourage us to get things done today. Right now! There's a ton of different apps that help manage our to-do lists and claim to make us more productive people. With so many options, how do you choose something that gets you down with GTD? Share your favorite productivity apps in the Engadget forums!